The present invention relates to the stripping, i.e. the cutting and removal of an end section of an outer sheath of electric, optical or other cables, and relates more generally to stripping of any cylindrical body protected by a flexible, or relatively flexible sheath.
The invention was developed in particular, but not exclusively, for the stripping of electric cables termed "constituted" cables comprising a plurality of layers of independent insulated conductors, twisted together, the strands thus formed being themselves protected by an outer protective, insulating or conductive sheath, and for the stripping of such constituted cables having an extra sheath which may comprise one or more insulated and/or screened conductors.
Cables of these types are mainly employed in technical fields in which a very high precision is absolutely imperative and, in order to connect such cables, previously cut to the desired lengths, it is necessary to strip their ends in such manner that the outer sheath is cut sharply and cleanly, in a perfectly radial manner, i.e. exactly at 90.degree. to their axis.
Many methods and apparatus are known for stripping the ends of electric cables, but none has an absolute reliability and/or none provides a sharp, clean and perfectly radial cutting quality.
Furthermore, the protection of the subjacent insulations, or sheaths, is not ensured in a mechanical or manual stripping apparatus when the thickness of the outer sheath is uneven--which is the case of many constituted cables--and the subjacent layers are then liable to be deteriorated either by an inadapted adjustment or by a defect in the manual dexterity of an operator.
FR-A-2,299,746 discloses a method and device for removing a section of given length of the screen (or the sheath) of a coaxial cable, in which the strands of conductors are inserted in a tubular cylindrical element, or punch, in such manner as to cause the element to pass under the screen, between the latter and the strands of the cable to be stripped, thereby creating an annular expansion of the screen in front of the end of the punch. The cable is passed through an opening of a die whose diameter is equal to the outside diameter of the screen, thereby resulting in a cutting of the latter around the cutting end of the punch. However, the cut obtained by means of this device is on a bevel owing to the fact that, in order to be able to cut the screen, the end of the punch must be chamfered. This device is therefore unsuitable for producing the desired sharp, radial cut.
FR-A-2,614,142 discloses another stripping device which is specially designed to strip a sheathed wire and comprises a tubular support in which the wire to be stripped is engaged and clamped, and a stripping assembly which is also tubular and includes cutting blades orthogonal to the axis of the wire and pivotally mounted so as to move toward or away from the conductor, and means for cutting the sheath axially. As most of the other known stripping devices, this device does not permit precisely controlling the depth of the cuts effected axially and radially, which, as far as this device is concerned, is only of relative importance, since there is no insulation around the conductor for which deterioration must be avoided.
This apparatus is also unsuitable for the purpose of the invention, which is to obtain a clean and sharp radial stripping with no risk of deteriorating the insulations of the subjacent conductors, while effecting a perfectly radial cut.
An object of the invention is to overcome these drawbacks of the known stripping devices for cables.